1. Field of the Invention
This invention relates to a container with a self-closing orifice in general, and more particularly to a pump dispenser which forces product out of a self-sealing spout.
Various types of pump dispensers have been developed particularly for dispensing, e.g., viscous products. A vacuum pump uses the stroke of a mechanism, which increases the pressure on the product within a pumping compartment, to force product out of the container. The mechanism's return stroke creates a partial vacuum in the pumping compartment in the space previously occupied by the dispensed product and draws product from a primary compartment into the pumping compartment. The primary compartment may be a vented compartment coupled to the pumping compartment via a dip tube. It may also be a non-vented, variable volume compartment. In one such variable volume device, a second mechanism (often a piston), acted upon by atmospheric pressure, maintains the primary compartment's reduced volume. Alternatively, the reduced volume may be accomplished with a flexible, collapsible bag also acted upon by atmospheric pressure.
The instant application is related to an improved vacuum pump dispenser which seals the spout after dispensing a controlled dosage.
2. Description of the Prior Art
In U.S. Pat. No. 4,457,454, issued July 3, 1984, I disclose a two-compartment dispenser. In the two-compartment dispenser, fluent material is transferred from a collapsible primary compartment through a valve-controlled passage to a pumping secondary compartment. The product is dispensed from there through a discharge nozzle (spout). Alternate depression and release of a resiliently biased part of the pumping compartment's wall causes this pumping action.
Two problems arise in a vacuum pump dispenser (such as the two compartment dispenser of my prior U.S. Pat. No. 4,457,454)--controlling dosage and preventing contamination. First, the reduction in the pumping compartment's volume should be accurately gauged to dispense a predetermined amount of product (a controlled dosage). Second, the outlet port (or spout through which the product exits) should be sealed after each use to prevent exposure of the product to the atmosphere, thus preventing contamination of the remaining product and decreasing the possibility of caked product blocking the spout. Preventing contamination is especially important when the pump container holds a perishable food product.
My U.S. Pat. No. 4,457,454 shows several alternate mechanisms for sealing the spout. One embodiment shows a cap with slots that are manually twisted to align with slots in a nozzle for opening the nozzle and to misalign for closing the nozzle. Another embodiment shows a sliding cap within the nozzle. Pressure on the product within the dispenser forces the cap to slide outwardly exposing a spout located near the cap's tip. Manual effort, however, is required to push in the cap to seal the spout. While these seals are acceptable for most applications, e.g.: hand lotions and toothpaste, where the spout need not be closed after each use, a self-opening and self-sealing spout is a much-needed improvement for many applications, e.g.: perishable food products, where the spout should be closed between each use.
The prior art shows several mechanisms for sealing a spout. The most primitive prior art uses a removable cap to seal the outlet port. This, of course, is not a self-sealing spout because the user must replace the cap after each use. Additional inconvenience arises when the cap is lost or misplaced.
In U.S. Pat. No. 3,010,613, issued Nov. 28, 1961, Stossel shows a self-sealing spout having two overlapping plastic lips which open outwardly when product is pressed out of the dispenser and close to prevent the intake of air when pressure upon the product in the dispenser is released. U.S. Pat. No. 3,223,289, issued Dec. 14, 1965, shows a collapsible bag using the overlapping lips concept.
In U.S. Pat. No. 3,088,636, issued May 7, 1963, Spatz shows a dispenser with two different embodiments of self-sealing spouts. The first embodiment, having a spout with two overlapping lips, uses the concept disclosed in the '613 patent. The second embodiment shows a spout with an external valve head biased into the spout by a spring. An increase in pressure upon the fluid within the dispenser causes the head to be displaced outwardly, so that fluid can escape. Upon release of the pressure, the spring returns the head to the sealing position.
In U.S. Pat. No. 3,268,123, issued Aug. 23, 1966, Spatz shows another dispenser with a self-sealing spout using an internal head. A mechanism, which also increases the pressure on the product, moves the head inwardly away from the dispenser's spout to create a gap through which product exits the dispenser. When the mechanism is released, a spring urges the valve member outwardly to seal the spout.